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When these different elements are collected under

their proper heads, we obtain

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1. Oxygen in carbonic acid ............ 42.86
inflammable air ........ 11.96

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7. The result of two other experiments on oxalate of line was very nearly the same as the preceding: The following may be stated in round numbers as the mean of the whole. Oxalic acid is a compound of

Oxygen
Carbon
Hydrogen

..... 64

32

4

100

8. The only other analysis of oxalic acid with which I am acquainted has been given by M. Fourcroy, as the result of his own experiments, in conjunction with those of Vauquelin. It is as follows:

* Systeme de Connois Chem, vol. VII. p. 224.

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It gave me considerable uneasiness to observe, that my experiments led to conclusions irreconcileable with those of chemists of such eminence and consummate skill, and it was not without considerable hesitation that I ventured to place any reliance upon them. I am persuaded, however, that some mistake has inadvertently insinuated itself into their calculations; since the carbonic acid alone, formed during the distillation of oxalate of lime, contains considerably more carbon than the whole quantity which they assign to the oxalic acid decomposed. M. Fourcroy informs us, that oxalic acid is converted into carbonic acid and water, when acted upon by hot nitric acid; and this decomposition seems to have been the method employed, to ascertain the proportion of the constituents of oxalic acid; but the numbers assigned by him do not correspond with this statement. For 10 parts of hydrogen require 60 of oxygen to convert them into water, and 13 of carbon require at least 33 of oxygen. So that instead of 77 parts of oxygen, there would have been required no less than 98 to convert the hydrogen and carbon into water and carbonic acid. It is true, that the surplus of oxygen may be conceived to be furnished by the nitric acid; but if this be admitted (and I have no doubt, from experience, that the nitric acid actually does communi◄ cate oxygen), it is difficult to see how the constituents of oxalic acid could be determined by any such decomposition, unless the quantity of oxygen furnished by the nitric acid were accurately ascertained,

IV. Composition of Oxalic Acid.

The knowledge of the relative weights of the ele ments which compose oxalic acid, though of importance, is not sufficient to convey a clear idea of this compound, and in what respect it differs from tartaric acid, alcohol, sugar, and various other bodies possessing very different properties, though composed of the very same elements in different proportions.

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It has been ascertained, by numerous and decisive experiments, that elementary bodies always enter into combinations in determinate proportions, which may represented by numbers. For example, the numbers which correspond to the four elements, oxygen, azote, carbon, and hydrogen, are the following:

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Now, in all compounds consisting of these ingredients, the proportion of the different constituents may always be represented by these numbers, or by multiples of them; thus, the composition of the following substances may be thus stated.

Oxygen. Hydrogen, Carbon, Azote,

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From the knowledge of this curious law, it is difficult to avoid concluding that each of these elements consist of atoms of determinate weight, which combine accord/ ing to certain fixed proportions, and that the numbers above given represent the relative weights of these atoms respectively. Thus, an atom of oxygen weighs six, an atom of hydrogen one, &c. Water is composed of one atom of oxygen and one atom of hydrogen; carbonic acid of two atoms of oxygen and one of carbon, &c. This curious theory, which promises to throw an unexpected light on the obscurest parts of chemistry, belongs to Mr. Dalton. I have elsewhere illustrated it at considerable length *.

The same low holds with respect to the salts. The acid and bases always combine in determinate proportions. We may affix numbers to all the acids and bases, which numbers, or their multiples, will represent all the combinations into which these bodies enter.

these numbers are given in the following table;

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These numbers may be conceived to represent the relative weights of an integrant particle of each of these substances; formed on the supposition that an atom of hydrogen weighs 1. It follows equally from this law, that the acids and bases combine particle with particle, or a certain determinate number of particles of the one with a particle of the other.

* See System of Chemistry, vol. III. p. 424, &c. third Edit.

One

One of the most important points in the investigation of compound bodies, is to ascertain the number which denotes the weight of an integrant particle of each of them, that of an atom of hydrogen being 1; because this number, or a multiple of it, represents the weight of each, which enters into all combinations, and because it enables us to estimate the number of elementary atoms of which each is composed. From a careful comparison of the table of oxalates, given in a preceding part of this paper, with the weight of the different bases already determined, it appears that the weight of an integrant particle of oxalic acid must be represented by the number 39.5.

Now, what number of atoms of oxygen, carbon, and hydrogen, go to constitute an integrant particle of oxalic acid? We have assigned the relative weights of each of these atoms, and we have ascertained the relative proportions of the respective elements of oxalic acid. From these data it is easy to solve the problem. An integrant particle of oxalic acid consists of 9 atoms combined together, namely 4 atoms of oxygen, 3 of carbon, and 2 of hydrogen.

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= 24

3 x 4.5 13.5

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2

39.5

For these weights, and the method of determining them, I refer the reader to my System of Chemistry, third Edit. vol. III. p. 619. The numbers which I have there assigned are, I am persuaded, rather too low.

'VOL. XIII. SECOND SERIES.

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